1. Field of the Invention
The present invention is directed to a pumping system for producing well fluids from petroleum producing formations penetrated by a well. Once aspect of the present invention includes the use of dual parallel tubing strings having the lower portions connected by a crossover flow connection, one of the tubing strings, i.e., the production tubing string, forming a flow path for flowing production fluids to the surface and the other, i.e., the power tubing string, for providing a conduit for inserting, operating and removing a rod-activated pump plunger-used to lift well fluids from the well and to move the well fluids up the well to the surface through the crossover flow connection. A flow control valve for controlling production flow is also provided. A lubricating plunger is provided to direct fluid from the annulus between the power tubing and the rods to an area between the barrel of the pump and the lubricating plunger to increase the efficiency of the pump and to assist in sand control.
Another aspect of the invention relates to the management of course particulate, such as sand, that may tend to accumulate between the plunger and the pump barrel. More particularly, this aspect of the invention relates to techniques for preventing or greatly reducing the amount of course particulate that may accumulate between the plunger and the pump barrel.
2. Description of Related Art
Pumping well fluids from wells penetrating producing formations has been done for many years. This is particularly true where heavy viscous oil must be moved to the surface. Often heavy viscous oils such as produced from California formations which are relatively close to the earth""s surface contain sand and are difficult to pump. Steam and diluents have often been used to lower the viscosity of heavy crudes to improve flow and pumping efficiency; however, sand is still a major problem.
Heretofore dual tubing strings for a pumping system for producing petroleum have been suggested. For example, pumping installations utilizing parallel dual tubing strings are disclosed in U.S. Pat. No. 4,056,335 to Walter S. Secrest; U.S. Pat. No. 3,802,802 to F. Conrad Greer; and U.S. Pat. No. 3,167,019 to J. W. Harris.
There is still need, however, for a pumping system having dual production and power tubing strings which permit ease of operation which has movable parts including the pump plunger which may be removed from the power tubing string and replaced in the tubing string without the-need for removing the tubing strings from the well, leaving only the pump barrel and tubing in place.
There is also a need for managing the location of course particulate, such as sand, that may exist in the fluids being pumped. Such techniques should be useful with pumping systems having both single and dual tubing strings.
The present invention provides apparatus for producing well fluids from an oil bearing formation penetrated by a well including production tubing means forming a production flow path for production fluids between the earth""s surface and a location in the well suitable for receiving well production fluids from a pump located in a parallel power tubing means. Flow control means are preferably located in the lower portion of the apparatus to permit flow of production fluids up the production flow path and to prevent flow of production fluids down the production flow path. Power tubing means extend down the well in parallel relationship with the production tubing means to a location in the well suitable for receiving production fluids into the lower portion of the power tubing means from said well. An insert or tubing-type lubricating plunger is provided, and the plunger is preferably adapted to be inserted and removed from the power tubing means while the power tubing means are located in the well. A standing valve is provided to permit entry of well fluids from the producing formation into the lower portion of the power tubing means. A crossover flow path is formed between the lower portion of the power tubing means and the flow path of the production tubing means for flowing production fluids out of the power tubing means and into the flow path of the production tubing means as the only flow path for transfer of production fluids to the earth""s surface. Rod means for operating the tubing-type pump are operatively connected to the pump. Preferably, the means for operating the pump includes a rod string extending down the power tubing means and operably connected to the plunger of the insert or tubing-type pump. The operative elements of the insert or tubing-type pump are preferably located in the well below the location of the flow control means. The pump barrel of the tubing-type pump is a lowest section of the power tubing string. A valve is provided for flowing lubricating fluid from the power tubing string into a hollow pull tube connecting the lower end of the rod string to a lubricating plunger of the pump. The lubricating plunger has flow ports for permitting flow of lubricating fluid from inside the plunger to the annulus between the outside of the plunger and the inside of the pump barrel. The plunger is used in the tubing pump to receive fluids from the pull tube to lubricate the pump, to improve its efficiency and to control sand from entering the area of between the plunger and barrel.
In a more specific aspect the present invention provides apparatus for pumping petroleum from a well penetrating a petroleum producing formation which includes a downhole assembly located in a well at a position adapted to receive petroleum fluids from the well. The downhole assembly includes a parallel anchor having a first passage and a second passage formed parallel to the central axis of the parallel anchor. Means are provided for mounting the parallel anchor in the well at the desired position and a tubular connecting pup is connected to the first passage of the parallel anchor and extends down the well. A flow control means such as a standing valve, or a sliding valve, which permits flow up the connecting pup tubing and prevents flow down the connecting pup tubing is connected in the lower portion of the apparatus, for example, in or near the connecting pup. A crossover flow head is connected between the lower end of the connecting pup tubing below the standing valve and an opening in the pump barrel to provide a flow path for petroleum from the pump barrel through the standing valve into the lower portion of the connecting pup tubing. A production tubing string extends from the earth""s surface down the well and is inserted into the first passage of the parallel anchor to form, in combination with the crossover flow head, the connecting pup tubing and a tubular string, a flow path to the earth""s surface for petroleum. A power tubing string is positioned in the well parallel to the production tubing string and extends through the second passage in the parallel anchor. Connecting means connect the lower end of the power tubing string to the upper end of the tubular landing nipple. A tubing-type seal off is inserted into the power tubing and landed in the tubular landing nipple. Means are provided to form a flow path for petroleum between the lower portion of the power tubing string and the lower portion of the production tubing string. Means are provided for disconnectably connecting the plunger of the tubing-type pump in operating position in the power tubing and the landing nipple for pumping fluid up the power tubing string to the flow path of the production tubing string. A lubricating plunger is provided for flowing lubricating fluid into the annulus formed between the pump barrel and a pump plunger.
The present invention provides an assembly which includes parallel power tubing and production tubing strings. A lubricating plunger is located inside and at the bottom of the power tubing string. The power tubing string connects to a bottom hole assembly with a crossover flow head which-connects with the production tubing string. This provides for flow of production fluids from the pump to the production tubing string. A rod string, connected to a pumping unit at the surface gives the lubricating plunger of the tubing-type pump an up-and-down motion for pumping the well fluid to the surface through this production tubing string. A xe2x80x9cBeardxe2x80x9d valve is connected at the lower end of the rod string. The xe2x80x9cBeardxe2x80x9d valve includes a port to permit fluid flow from the power tubing annulus into the interior of the xe2x80x9cBeardxe2x80x9d valve. A hollow pull tube is connected to the lower end of the xe2x80x9cBeardxe2x80x9d valve and extends to and is connected to the lubricating plunger to provide for flow of lubricating fluids to the plunger. The plunger has ports for flowing the lubricating fluid out into the annulus between the plunger and the pump barrel. Thus, diluent or water with a surfactant may be placed in the power tubing for use in lubrication of the tubing pump to improve the efficiency thereof and to prevent sanding up of the pump.
The present invention utilized a tubing insert plunger. Thus, the plunger of the pump is connected to the rod string and is inserted inside the power tubing string. The lowermost section of the power tubing string forms the barrel of the pump. Generally, only the rod stringer has to be pulled to retrieve all moving and wearable pump parts except for the pump barrel. Thus, the apparatus of the present invention will save rig time when pump repairs or replacement is needed. Also because the production flow path is separated from the pumping rod string, the apparatus of the present invention will never have a floating rod problem. It will also eliminate inertia bars and require smaller less expensive rods. In addition, lubricating fluid may be injected down the power tubing string through the xe2x80x9cBeardxe2x80x9d valve and the hollow pull tube rod and into a lubricating plunger of the pump. The lubricating plunger is provided with ports to direct the fluid coming from the hollow pull tube into the area between the plunger and pump barrel. Increasing the pressure in the annulus of the power tubing to exceed that of the production tubing keep sand out of the area between the plunger and pump barrel and to increase pump efficiency.
In one exemplary embodiment, the invention provides an apparatus for producing well fluids from an oil bearing formation penetrated by a well. The apparatus comprises a production tubing string which forms a production flow path for production fluids. The production tubing string is configured so that it may be positioned between the earth""s surface and a location in the well suitable for receiving well production fluids. A power tubing string is also provided and includes an upper portion and a lower portion. The power tubing string extends down the well in a generally parallel relationship with the production tubing string to a location in the well suitable for receiving production fluids into the lower portion of the power tubing string. A pumping apparatus is disposed in the power tubing string to pump well fluids from the well into the lower portion of the power tubing string. Further, a crossover flow mechanism is provided between the lower portion of the power tubing string and the flow path of the production tubing string to divert the flow of production fluids out of the power tubing string and into the flow path of the production tubing string where it may be transferred to the earth""s surface. A lubricant flow path is also provided and extends from the earth""s surface to a location near the pumping mechanism to allow lubricants to be introduced into the pumping mechanism. In this way, lubricants may be provided to the pumping mechanism to substantially hinder undue wear that may be caused by sand or other coarse particulate found within the production fluids.
In one particular aspect, the production flow path has a smaller cross-sectional area than the lower portion of the power tubing string to increase the velocity of the production fluids when diverted into the production flow path. In this way, sand or other coarse particulate within the production fluids will remain suspended and will not tend to settle within the tubing strings to hinder operation of the apparatus.
Two different arrangements of the lubricant flow path may be provided to supply lubricant to the pumping mechanism. In one alternative, the lubricant flow path may pass through substantially the entire length of the power tubing string. More specifically, the lubricant flow path may pass through the crossover flow mechanism. In this way, the overall size of the power tubing string may be reduced. In one particularly preferable implementation, the lubricant flow path will pass through at least one rod which extends through the power tubing string and which is used to operate the pumping mechanism.
In the second alternative, the lubricant flow path may be arranged to bypass the crossover flow mechanism. For instance, a side tubing string may be provided to bypass the crossover flow mechanism. The side tubing string will preferably have a bottom end which is connected to a lower portion of the power tubing string near the pumping mechanism so that the lubricant may be provided to the pumping mechanism.
With both the passthrough and bypass embodiments just described, a variety of pumping mechanisms may be employed. For example, the pumping mechanisms may comprise an insert pump, a progressive cavity pump, a tubing pump, and the like.
In another aspect, the invention provides techniques for managing course particulate, such as sand, within a pumping system. For example, in one embodiment, the invention provides a pumping system that comprises a pump barrel that is placed into a well casing. A plunger is reciprocatably positioned within the pump barrel and has an open top end, a bottom end, and a traveling valve at the bottom end. A connector is coupled to the plunger below the top end. Further, a rod is coupled to the connector and is translatable to reciprocate the plunger within the pump barrel using an upstroke and a downstroke. Upon each upstroke, the top end of the plunger directs particulate into the plunger and away from the pump barrel.
In one particular aspect, the plunger comprises a cylinder having an open top end that is inwardly tapered. Further, the connector is disposed within the cylinder. In this way, as the plunger is moved upward, the tapered top end funnels the particulate into the plunger and away from the pump barrel. In another aspect, the connector has at least one through hole to permit fluids to be moved upwardly through the connector and the plunger upon each downstroke of the plunger. In still another aspect, the pump barrel has a bottom end and a standing valve in the bottom end.
The invention also provides an exemplary method for pumping fluids from the ground. According to the method, a pumping system is placed into the ground and comprises a pump barrel and a plunger reciprocatably positioned within the pump barrel. The plunger has an open top end, a bottom end, and a traveling valve at the bottom end. The system further includes a connector that is coupled to the plunger below the top end. With such a configuration, the plunger is reciprocated within the pump barrel with an upstroke and a downstroke, and particulate is directed into the plunger through the open top end and away from the pump barrel upon each upstroke.
In one aspect, the plunger comprises a cylinder having an inwardly tapered open top end to direct particulate into the cylinder upon each upstroke. In another aspect, the plunger has a traveling valve at the bottom end, and the pump barrel has a standing valve at a bottom end. In this way, fluids are drawn into the pump barrel through the standing valve upon each upstroke and are forced through the traveling valve upon each downstroke. In yet another aspect, the connector has a through hole such that fluids passing through the traveling valve move through the through hole and upwardly through the plunger.
A principal object of the present invention is to provide a pumping system having parallel power tubing and production tubing strings in which production is flowed up the production tubing through a flow control valve connected at the lower end of the pumping system. A rod operated insertable and removable pump plunger is disconnectably connected into the power tubing wherein the pump plunger may be removed from and inserted into the power tubing without the need to remove the tubing string from the well. A hollow pull tube is connected to the lower end of the rod string by a xe2x80x9cBeardxe2x80x9d valve and used to operate the pump plunger and also to provide a source of lubricating fluid for the lubricating plunger of the pump. The plunger has ports for flowing the fluid into the area between the pump barrel formed by the lower end of the power tubing and the outside of the plunger with increased pressure in the pump annulus to inhibit sand production and to increase pump efficiency. The increased pressure is accomplished by appropriate surface mechanism such as a pump.
Another object of the invention is to provide techniques for eliminating or greatly reducing the presence of course particulate between the pump barrel and the plunger. Additional objects and advantages of the present invention will become apparent to those skilled in the art from the drawings which are made a part of this specification and the detailed description of the invention.